Function (including brief description) | Mammalian-specific characteristics | Yeast-specific characteristics |
---|---|---|
Phosphatidylserine (PS) Transfer: PS is made on the ER, but transferred to mitochondria for the production of phosphatidylethanolamine (PE) [4, 84] | PS transfer occurs on a triple contact site between ER, OMM and IMM [25–27], requires ATP [90] and cytosolic Ca2+ [91]. | PS transfer occurs at ER mitochondria contact sites [96], but does not require ATP [17, 97]. PS transfer is not obligatory, since Psd2p can replace mitochondrial PE production [98, 99]. |
Role of sterols on MAM | MAM has lipid raft characteristics and is marked with caveolin [116–122]. ORP5 and ORP8 form a protein bridge with mitochondrial PTPIP51 [130]. | No raft characteristics known as of today [123]. |
Ca2+ handling at the MAM; mitochondria receive Ca2+ from the ER upon formation of a Ca2+ microdomain [155–163] | Mitochondria import Ca2+ via the mitochondrial Ca2+ uniporter (MCU) [148–150]. Ca2+ is required for mitochondrial dehydrogenases [132] and respiration [133]. | No MCU present [148–150]. Ca2+ is required for mitochondrial dehydrogenases [151]; increase of Ca2+ in the cytoplasm boosts mitochondrial respiration [194]. |
MAM Ca2+ signaling in apoptosis | Ca2+ is released from the ER [193]. | |
ER chaperones on the MAM | ER chaperones on the MAM control MAM Ca2+ transfer and cytosolic Ca2+ waves [180–188]. | None detected. |
Currently known MAM tethers or proteins regulating MAM tethering | PACS-2 [38, 40], mitofusin-2 [42–45], BAP31/Fis1 (ARCosome) [41], IP3R/VDAC/Grp75 [73], PTPIP51/VAPB [74–76] PERK [65, 66] | |
MAM and mitochondrial fission | Drp1 oligomerizes on MAM to mediate mitochondria fission [15] | Drp1 oligomerizes on MAM to mediate mitochondria fission [15] |
MAM as point of origin for autophagy | MAM is material for isolation membrane [16]. Implicated MAM proteins are calnexin, Drp1, FUNDC1 [220], Rab32, syntaxin-17 [222, 223], PACS-2, mitofusin-2 [16] | ERMES mutants show no defect in Atg8p recruitment, but are defective in mitophagy and lipid supply for phagophore formation [22, 224] |